Nick Ayers, currently chief of staff to Mike Pence, has been seen as Trump’s first choice to succeed Kelly, whose long-expected departure had been trailed last week through yet more political drama, in which Trump announced new picks for attorney general, UN ambassador and chairman of the joint chiefs of staff and weathered damaging developments in the Mueller investigation into the Trump campaign’s links with Russia.

But late on Sunday, Ayers tweeted his thanks to Trump, the vice-president “and my great colleagues for the honor to serve our nation at the White House. I will be departing at the end of the year but will work with the #MAGA team to advance the cause.”

Trump’s administration has set records for staff turnover, and he has often struggled to attract experienced political professionals, a challenge that has grown more difficult by the upcoming threat of costly Democratic oversight investigations next year and an uncertain political environment.

On Saturday, the president told reporters at the White House Kelly would leave by the end of the year. On Sunday, citing unnamed White House officials, the Wall Street Journal and other outlets said Trump and Ayers had failed to agree on terms on the length of his service.

Ayers, 36, is the father of young triplets and has reportedly long planned to leave the administration at the end of this year and return to his home in Georgia. The Journal reported that he had not been able to commit to the White House job beyond the spring of 2019. Citing an anonymous source, the Associated Press said Ayers would now run a pro-Trump group.

The Journal and other outlets had reported that Trump’s preference for Ayers, reportedly an ally of the president’s daughter Ivanka Trump and her husband Jared Kusher, had caused dissent in the West Wing.

Trump is reported to want a chief of staff – his third, after the former Republican National Commitee chair Reince Priebus and Kelly, a retired Marine Corps general – in place through to the 2020 election. Priebus and Kelly both struggled to impose order on an impetuous president and an unruly, factionalised White House.

In any administration, the role of White House chief of staff is split between the responsibilities of supervising the White House and managing the man sitting in the Oval Office. Striking that balance in the turbulent times of Trump bedeviled both Kelly and Priebus, and will be the defining challenge for whomever is selected next.

On Sunday night Trump said on Twitter that he was interviewing “some really great people” for the key role.

Donald J. Trump (@realDonaldTrump)

I am in the process of interviewing some really great people for the position of White House Chief of Staff. Fake News has been saying with certainty it was Nick Ayers, a spectacular person who will always be with our #MAGA agenda. I will be making a decision soon!

Trump’s search for the high-profile hire comes at a pivotal time as the president looks to prepare his White House for the twin challenges of securing his re-election in 2020 and fending off inquiries once Democrats gain control of the House next year.

The New York Times reported on Saturday that the treasury secretary, Steven Mnuchin, budget director, Mick Mulvaney, and US trade representative, Robert Lighthizer, were other possible choices to be chief of staff.

On Sunday, the AP said an anonymous source “with knowledge of the president’s thinking” confirmed Mulvaney was one of four people under consideration.